Time Graph Research Articles

Representation of superposition of two technical systems with a density function centroid

Aim. The practice of dependability calculation and analysis occasionally deals with technical systems for which the dependability model is difficult or impossible to adequately describe with a set of serial and parallel connections and corresponding mathematical tools of multiplication of probabilities. The article examines the method of modeling the dependability of highly integrated systems through the analysis of the position of time to failure density function centroid f(t). This work is the continuation of a big research dedicated to the analysis of the properties of a density function centroid in highly integrated technical systems. In the first part it was shown that the centroid allows identifying the level of mutual influence of subsystems of a mechatronic system and identifying their contribution into the overall level of dependability of a whole product, where the primary criterion is the proximity of the partial centroid of the density function of each subsystem to the overall average centroid of the whole system. This paper assumes that the average centroid for a composition of density functions of product components does not depend on the way they are connected in the dependability model and thus can be used as the conditional reliability indicator for systems with fuzzy structural and functional connections. Methods. The research is based on graphs of time to failure density functions for conditional components of a complex technical system, such as electronics, mechanics and software. The diverse nature of the system’s components is reflected through the variation of parameters of the Weibull-Gnedenko law. In order to simplify the calculation and presentation of the results, the analysis is conducted not in an integrated manner for 3 components, but for pairs. For each pair of subsystems density functions are calculated and plotted both for individual components, and for cases of their serial and parallel connection. Then, for each calculation case the centroid of the corresponding density function is generated with subsequent plotting and comparison of the average graphs. Results. The primary observation based on the results of the graph analysis is that the average centroid resulting from two partial centroids of the density functions of single systems (mechanics, electronics, software) has a high rate of correlation (over 0.99) and almost matches the average centroid generated out of two partial centroids of serial and parallel connection of the respective pairs of systems per each calculation case. Conclusions. The results of the research again show that the average centroid for a composition of density functions of different systems is equivalent to their superposition and can be used as a conditional average (or fuzzy) index of the overall level of dependability of highly integrated complex technical systems of which the structural and functional dependability model is difficult to represent with a set of serial and parallel connections and corresponding mathematical tools of multiplication of probabilities.

Integer programming approach to static monopolies in graphs

A subset M of vertices of a graph is called a static monopoly, if any vertex v outside M has at least $$\lceil \tfrac{1 }{2}\deg (v)\rceil $$ neighbors in M. The minimum static monopoly problem has been extensively studied in graph theoretical context. We study this problem from an integer programming point of view for the first time and give a linear formulation for it. We study the facial structure of the corresponding polytope, classify facet defining inequalities of the integer programming formulation and introduce some families of valid inequalities. We show that in the presence of a vertex cut or an edge cut in the graph, the problem can be solved more efficiently by adding some strong valid inequalities. An algorithm is given that solves the minimum monopoly problem in trees and cactus graphs in linear time. We test our methods by performing several experiments on randomly generated graphs. A software package is introduced that solves the minimum monopoly problem using open source integer linear programming solvers.

Using Behavior Over Time Graphs to Spur Systems Thinking Among Public Health Practitioners.

Public health practitioners can use Behavior Over Time (BOT) graphs to spur discussion and systems thinking around complex challenges. Multiple large systems, such as health care, the economy, and education, affect chronic disease rates in the United States. System thinking tools can build public health practitioners’ capacity to understand these systems and collaborate within and across sectors to improve population health. BOT graphs show a variable, or variables (y axis) over time (x axis). Although analyzing trends is not new to public health, drawing BOT graphs, annotating the events and systemic forces that are likely to influence the depicted trends, and then discussing the graphs in a diverse group provides an opportunity for public health practitioners to hear each other’s perspectives and creates a more holistic understanding of the key factors that contribute to a trend. We describe how BOT graphs are used in public health, how they can be used to generate group discussion, and how this process can advance systems-level thinking. Then we describe how BOT graphs were used with groups of maternal and child health (MCH) practitioners and partners (N = 101) during a training session to advance their thinking about MCH challenges. Eighty-six percent of the 84 participants who completed an evaluation agreed or strongly agreed that they would use this BOT graph process to engage stakeholders in their home states and jurisdictions. The BOT graph process we describe can be applied to a variety of public health issues and used by practitioners, stakeholders, and researchers.

Issue Cover (February 2018)

Front cover: Background: Alcohol abuse disorders are associated with adverse neurological symptoms and neurotoxicity. However, despite being one of the most commonly abused substances, the physiological effects of ethanol are not well defined. Main finding: By combining Drosophila, an ideal system for modelling ethanol disorders given their strong homology with mammals and natural response to ethanol, with high spatiotemporal resolution live-imaging of vesicle motility, we found that acute, low doses of ethanol result in increased flux of fluorescently-labeled neuropeptide vesicles toward neuromuscular junctions. Pharmacological treatments to increase (wortmannin) or decrease (LiCl) active GSK-3 levels revealed that GSK-3 is critical in mediating this stimulatory effect of ethanol. Implications: These results yield novel insight into the neurophysiological effects of ethanol and provide a possible link between behavioral responses to ethanol and neuropeptide transport. Image content: Time (y axis, 30 seconds) versus distance (x axis, 90 μm) graph of real-time movement of GFP-tagged neuropeptide vesicles in living Drosophila larvae. The reduced vesicle motility by wortmannin feeding is partially rescued by acute treatment with low dose ethanol. Read the full article ‘Ethanol stimulates the in vivo axonal movement of neuropeptide dense-core vesicles in Drosophila motor neurons’ by G. J. Iacobucci and S. Gunawardena (J. Neurochem. 2018, vol. 144(4), pp. 466–482) on doi: 10.1111/jnc.14230

Comparison of the Growth of $${\text {TiO}}_{2}$$ TiO 2 Nanotubes in Different Solutions

The kinetics of growth of tubular nanostructures of titanium dioxide ( $${\text {TiO}}_{2}$$ ) obtained by means of the physic-chemical method of electro position under potentiostatic conditions is studied. For this investigation, four tests were carried out where some synthesis parameters were varied in chemical solution: water/fluorhydric acid/ammonium fluoride/ethylene glycol $$(\text {H}_{2} \text {O/HF/NH}_{4}\text {F/EG})$$ as well as the conditions of anodization. Therefore, the chemical attack in the anodization process is produced by the $$\text {NH}_{4}\text {F}$$ and $$\text {HF}$$ ions. The morphology of the resulting nanotubes was analyzed through scanning electron microscopy (SEM). The average length of the nanotubes was established, with a maximum value of 980 nm. By means of X-ray diffraction of the samples the structure was analyzed, obtaining a mixed phase of anatase and titanium. Using ultraviolet–visible spectroscopy (UV–Vis), the energy gap of the tests was found at different times of anodization. At 60 min of anodization, the energy gap of the samples varied between 3.56 and 3.68 eV. For a time of 30 min anodization, the energy gap of the samples varied between 3.58 and 3.63 eV with the same parameters of chemical synthesis. With obtaining of the curves of the current as a function of the time of anodization (I vs. t), the different stages of growth of the nanotubes and the regions that these stages define were determined. Analyzing of the behavior the current–time graphs and SEM measurements, it was observed that the best solution of the 4 tests used in this work was that of test 1.

Speedometer app videos to provide real-world velocity–time graph data 1: rail travel

The use of modern rail travel as a source of real-life velocity–time data to aid in the teaching of velocity and acceleration is discussed. A technique for using GPS speedometer apps to produce videos of velocity and time figures during a rail journey is described. The technique is applied to a UK rail journey, demonstrating how students can use its results to produce a velocity–time graph from which acceleration and deceleration figures can be calculated. These are compared with theoretical maximum figures, calculated from the train’s technical specification.

Firing Rate Optimization of Deterministic Timed Event Graphs by Server Performance Improvement

Timed event graphs are a subclass of Petri nets that are commonly applied for modeling and controlling manufacturing systems. In this paper, we investigate the problem of improving the performance of machines (servers) in timed event graphs in order to maximize the firing rate of a system. We show that the logic constraints on the cost of machines and the operation time of machines (firing delay of transitions) can be transformed into linear algebraic constraints. Furthermore, we formulate a mixed integer linear programming problem to maximize the firing rate of the net under a given budget for improving the performance of servers (decreasing the firing delay of transitions) that can provide an optimal solution. Finally, application to an assembly line is presented to show the effectiveness of the developed methodology.

Dissolution studies of Na2O-BaO-CaO-P2O5 glasses in deionized water under semi-dynamic conditions for bioactive applications

The phosphate glasses of composition Na2O-CaO-P2O5 are widely accepted glass material for biomedical applications. The glass samples with composition (26-x)Na2O-xBaO-29CaO-45P2O5 (x = 0,5,10,15) are prepared at 1100°C by melt-quenching technique. In order to reduce the fast dissolution rate, which limits their application, BaO is added by reducing Na2O composition. The dissolution studies have been carried out in deionized water under semi-dynamic conditions at 37°C for 14 days. The properties are studied based on Barium composition and time of immersion. The samples are taken out at 24 hrs. intervals to carry out weight loss and pH measurements. The rates of cation (Na+ and Ca2+) release from the glass to the solution were found out using flame photometer. The release of orthophosphate (PO43-) anions is measured by UV-Visible spectrometer using phospho-molybdenum blue method. The weight losses linearly increase with time for all the compositions. The addition of barium decreases the weight loss in deionized water. The pH of the solutions varies with dissolution of ions. The dissolution rate has been found out from the slope of the weight loss vs time graph and it decreased with increase in barium content

Gas response of tin oxide film sensor to varying methane gas concentration

This study was aimed to determine the effect of methane gas concentration on the voltage response of tin oxide (SnO2) film. The sensing circuit of the tin oxide film was interfaced to a laptop computer throug an arduino microcontroller for data acquisition. Real time data table and graph can be visualized on the laptop screen during the gas sensing process.The sensor was enclosed in an airtight plastic jar container connected to a gas source and a water trap that maintained atmospheric pressure in the chamber. A mixture of 1% methane in helium was introduced into the chamber at a rate of 2 liters per minute (LPM) using a mass flow controller. The gas mixture was introduced intermittently at several stages. Each stage was followed by a standby stage during which there was no gas flow and the sensor was allowed to equilibrate with the gas mixture. It was observed that during the introduction of gas at each stage the voltage output of the sensor was increasing. During the standby stage there was no observed change in the voltage output as indicated by a flat response in the graph of voltage output versus time. The added quantity of gas can be computed from the flow rate and time duration of each stage. The incremental concentration of gas was also computed after each succeeding stage.The computed concentration in parts per million (ppm) was plotted with the measured voltage output per stage. Results showed a linear relationship between gas concentration and voltage output in the range of 3.75 to 7.8 ppm with a linearity of 0.99 and sensor sensitivity of 140 mV/1000 ppm. The sensitivity and linearity were 161 mV/1000 ppm and 0.98, respectively in the range 1000 to 9000 ppm. It is recommended to conduct more trials at different concentration ranges, different methane input mixture percentages, and different flow rates.

Relating language, logic, and imagery

The world is a continuum, but words are discrete. Sensory organs map the continuous world to continuous mental models of sights, sounds, actions, and feelings. Those mental models, which represent a moving 3-D virtual reality (VR) are the semantic foundation for all versions of language and logic. A common model for cognition must be able to process and relate all modalities. Kyndi technology represents all information in graphs. They include conceptual graphs for symbolic information and arbitrary graphs for 2-D icons or 3-D VR. All graphs are stored in Cognitive Memory, which can find approximate mappings for arbitrary graphs in logarithmic time. Those mappings include formal unification for logics, and informal analogies for case-based reasoning. The analogies can even map conceptual graphs to the graphs derived from imagery or VR simulations. For reasoning, Peirce’s rules of inference for existential graphs can support operations on arbitrary icons, such as the diagrams in Euclid’s geometry. Those rules, when adapted to conceptual graphs, can map symbolic languages to and from Euclidean style geometrical reasoning. With two new rules of inference, called observation and imagination, the Standard Model of Cognition can support mental models without making any current software obsolete.

Synthesis of carbon nanoparticles in combined RF-DC plasma

In this work carbon nanoparticles were synthesized in combined RF-DC plasma. To synthesize carbon particles a graphite target was used. The time of synthesis of carbon particles was fixed using a self-bias voltage (Vdc). The SEM image and the chemical composition of the samples were obtained, and the particle size distribution was constructed. SEM images show synthesized spherical nanoparticles with diameters from 80 to 500 nm in dependence on plasma parameters. Self-bias voltage dependence on time at different plasma parameters (gas pressure and discharge power) has been obtained. The graph of particle synthesis time and DC voltage was shown. It was determined that the increase of DC voltage leads to the decreasing of particle synthesis time. Thus, one can conclude that growth of particles in plasma medium can be controlled by DC voltage value.

The Mutagenic Study of Benzimidazole Analogues: Structure-Activity Relationship (SAR)

Event Abstract Back to Event The mutagenic study of benzimidazole analogues: structure-activity relationship (SAR) Nurul Hafizan Azahar1, Siti Soleha Abdullah1, Rozaini Abdullah2, Norizan Ahmat3 and Hasiah Ab Hamid1* 1 Department of Biomedical Sciences, Faculty of Medicine and Health sciences, University of Putra Malaysia, Malaysia 2 Department of Environmental and Occupational Health, Putra Malaysia University, Malaysia 3 School of Chemistry and Environment, University Technology Mara, Malaysia Background Benzimidazole analogues have diverse range of biological activities including anti-ulcer, anti-hypertensive, anti-viral, anti-fungal, anti-inflammatory and anti-cancer. Previous studies revealed some of the analogues can induce mutation despite their biological activities. This study aims to screen for potential mutagenic activities of novel benzimidazole analogues using Ames test and study their structure-activity relationship (SAR). Methods Ames test was carried out on two strains of Salmonella typhimurium; TA98 and TA100 that carry different mutations in their various genes in histidine operon, which protocols complied with OECD 471 Guideline for Testing of Chemicals. The preliminary tests including growth curve and genetic analysis were carried out prior to Ames test in order to determine the optimum incubation hour and genotypes of the bacterial strains respectively. The bacterial growth curve was carried out by incubating the bacterial suspension for 52 hours. The optical density of the bacteria was recorded for every two hours at 660nm wavelength and the graph of optical density versus time was plotted. The genotypes of the bacterial strains used were determined by genetic analysis which includes tests on dependency on histidine and/or biotin, presence of rfa mutation, urvB deletion as well as pKM101 plasmid. All data were analysed using Two-Way ANOVA, followed by post-hoc Tukey test. The SAR was analysed based on the results of Ames test. Results The optimum incubation hour for both strains was 14 hours. Both bacterial strains show dependency on histidine with presence of rfa mutation, urvB deletion and pKM101 plasmid. Besides, all analogues tested; NN-1-5, NN-1-7, NN-1-9 and NN-1-18 show no mutagenic activity. Conclusion There was no significant difference in the mutagenic activity among all analogues despite their difference in the number and position of hydroxyl groups. Keywords: benzimidazole, Ames test, Salmonella typhimurium, Structure-activity relationship (SAR), MUTAGENIC Conference: International Conference on Drug Discovery and Translational Medicine 2018 (ICDDTM '18) “Seizing Opportunities and Addressing Challenges of Precision Medicine”, Putrajaya, Malaysia, 3 Dec - 5 Feb, 2019. Presentation Type: Poster Presentation Topic: Cancer Citation: Azahar N, Abdullah S, Abdullah R, Ahmat N and Ab Hamid H (2019). The mutagenic study of benzimidazole analogues: structure-activity relationship (SAR). Front. Pharmacol. Conference Abstract: International Conference on Drug Discovery and Translational Medicine 2018 (ICDDTM '18) “Seizing Opportunities and Addressing Challenges of Precision Medicine”. doi: 10.3389/conf.fphar.2018.63.00012 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Sep 2018; Published Online: 17 Jan 2019. * Correspondence: Dr. Hasiah Ab Hamid, Department of Biomedical Sciences, Faculty of Medicine and Health sciences, University of Putra Malaysia, Kuala Lumpur, Malaysia, hasiah@upm.edu.my Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Nurul Hafizan Azahar Siti Soleha Abdullah Rozaini Abdullah Norizan Ahmat Hasiah Ab Hamid Google Nurul Hafizan Azahar Siti Soleha Abdullah Rozaini Abdullah Norizan Ahmat Hasiah Ab Hamid Google Scholar Nurul Hafizan Azahar Siti Soleha Abdullah Rozaini Abdullah Norizan Ahmat Hasiah Ab Hamid PubMed Nurul Hafizan Azahar Siti Soleha Abdullah Rozaini Abdullah Norizan Ahmat Hasiah Ab Hamid Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Model Decomposition of Timed Event Graphs under Partial Synchronization in Dioids

Timed Event Graphs (TEGs) are a graphical model for decision free and time-invariant Discrete Event Systems (DESs). To express systems with time-variant behaviors, a new form of synchronization, called partial synchronization (PS), has been introduced for TEGs. Unlike exact synchronization, where two transitions t1, t2 can only fire if both transitions are simultaneously enabled, PS of transition t1 by transition t2 means that t1 can fire only when transition t2 fires, but t1 does not influence the firing of t2. Under some assumptions, we can show that the dynamic behavior of a TEG under PS can be decomposed into a time-variant and a time-invariant part. The time-invariant part can be interpreted as a standard TEG. Moreover, it is shown that the tools introduced for standard TEGs can be used to analyze the overall system.

Approximated Timed Reachability Graphs for performance evaluation and control of DES

This paper is about the performance analysis and control issues for discrete event systems (DESs) including time specifications and modeled with time Petri nets (TPNs). Petri nets are known as efficient mathematical and graphical models that are widely used to describe distributed DESs including choices, synchronizations and parallelisms. The domains of application include but are not restricted to manufacturing systems, computer science and transportation networks. Incorporating the time in the model is important to consider many control problems. This paper proposes an algorithm to design in a systematic way exact approximated timed reachability graphs that encode all feasible timed trajectories at a given accuracy under earliest firing policy. Some applications of these graphs are discussed.

Localization of time shift failures in (max,+)-linear systems

The goal of this paper is to propose a localization method of time shift failures in timed discrete event systems (TDES) called (max, +)-linear systems and graphically represented by Timed Event Graph (TEG). First, a detection process produces indicators that determine whether such failures have happened by the observation of incoming and outcoming timed flows. Then, thanks to the knowledge of the behavior of the system through its corresponding TEG, set of failures that could explain the detected timed shift are obtained. It comes from matrices of signatures for each indicator built on each observable output of the system.

Effect of Induced Geometric Non-Linearity in a Spring on Vehicle Ride Comfort and Road Holding

Suspension system is one of the most crucial components of any automobile. The present years have seen a drastic change in the design of a typical suspension system, mainly taking into account the critical aspects such as rider comfort and vehicle handling. A good suspension system should be able to provide a compromise between both of rider comfort and road holding. The spring design plays a major role in determining the optimum level of suspension performance. This paper focuses on the study of the effect that is caused on the values of those attributes that determine the rider comfort and road holding, by changing the spring design framework. A spring is taken and re-modeled by changing minor geometrical attributes and simulated on a 2 DOF passive suspension system modeled on MATLAB-SIMULINK to obtain time graphs to assess the ride comfort and road holding. The present work deals with inducing geometric non-linearity in the spring by changing its geometry and to study its direct effects on the suspension parameters.

An Eco-Friendly Efficient Cloud-Searching Technique With Delay

The authors propose a cloud-based disk-searching technique with delay in this article. Cloud computing is responsible for eco-friendly use of computers and other related resources. The proposed technique exerts less energy to search particular data. The searching technique finds a particular element through parallel channels. The energy efficiency is directly proportional to the number of channels for a specific set of data. The parallel searching technique is implemented to reduce time complexity and complexity of delay. The article exhibits a complexity of delay in a real-time scenario. The delay is depending upon the number of elements and if the number of elements is increased, then the overall delay is also increased. A time graph represents the relations between the number of elements and the number of channels. An energy-efficiency graph is also represented with respect to the number of channels. The delay is calculated with respect to the number of elements, cloud network delay, and waiting time for previous data execution. The authors have established relations between the delay and the number of elements, waiting time, and the cloud network delay.

Maximum weight independent set for [formula omitted]claw-free graphs in polynomial time

For a finite, simple, undirected graph G with a vertex weight function, the Maximum Weight Independent Set (MWIS) problem asks for an independent vertex set of G with maximum weight. MWIS is a well-known NP-hard problem of fundamental importance. For claw-free graphs, MWIS can be solved in polynomial time—in 1980, the first two such algorithms were independently found by Minty for MWIS and by Sbihi for the unweighted case. For a constant ℓ≥2, let ℓG denote the disjoint union of ℓ copies of G.In this paper, using a dynamic programming approach (inspired by Farber’s result about MWIS for 2K2-free graphs), we show that for any fixed ℓ, MWIS can be solved in polynomial time for ℓclaw-free graphs. This solves the open cases for MWIS on (P3+claw)-free graphs and on (2K2+claw)-free graphs and extends known results for claw-free graphs, ℓK2-free graphs, (K2+claw)-free graphs, and ℓP3-free graphs.

Effect of Atrazine Contamination on Compressibility and Permeability Characteristics of Clay

Abstract Atrazine (ATZ) is one of the most heavily used herbicides in the world, particularly in the United States and Australia. This study evaluated the compressibility and permeability characteristics of two Western Australia natural clays contaminated with varying ATZ contents. A series of one-dimensional consolidation tests using fixed-ring oedometer device were conducted, and the final hydraulic conductivity was calculated at the end of each loading stage. At the first stage, the strain–time graphs at 1,280 kPa effective overburden pressure (σ′n) were evaluated, and the results indicated that the specimens with a greater ATZ content have higher values of final vertical strain (ϵv). Then, the compression index (Cc) values were computed from the void ratio–effective overburden pressure curves (e−σ′n), and the results showed that the compression index (Cc) increased as the ATZ content of the tested clays increased. At the next stage, the coefficient of consolidation (cv) was calculated using the Casagrande method and the Taylor method. The results showed that the computed coefficient of consolidation (cv) using the Taylor method was slightly greater than those calculated using the Casagrande method in both tested clays. Also, the hydraulic conductivity (k) values of the tested clays increased as the contamination content increased (i.e., 3.1 × 10-7 ≤ k ≤ 129 × 10-7 cm/s and 4.49 × 10-9 ≤ k ≤ 95.3 × 10-9 cm/s). This behavior, which was attributed to promotion of the agglomeration and aggregation between clay particles, promoted formation of the tiny voids in the soil. Finally, the secondary compression ratio (Rα) and secondary compression index (Cα) were computed, and the results showed that the specimens containing higher ATZ content had greater values of Rα and Cα.

Causality and Temporal Dependencies in the Design of Fault Management Systems

Reasoning about causes and effects naturally arises in the engineering of safety-critical systems. A classical example is Fault Tree Analysis, a deductive technique used for system safety assessment, whereby an undesired state is reduced to the set of its immediate causes. The design of fault management systems also requires reasoning on causality relationships. In particular, a fail-operational system needs to ensure timely detection and identification of faults, i.e. recognize the occurrence of run-time faults through their observable effects on the system. Even more complex scenarios arise when multiple faults are involved and may interact in subtle ways. In this work, we propose a formal approach to fault management for complex systems. We first introduce the notions of fault tree and minimal cut sets. We then present a formal framework for the specification and analysis of diagnosability, and for the design of fault detection and identification (FDI) components. Finally, we review recent advances in fault propagation analysis, based on the Timed Failure Propagation Graphs (TFPG) formalism.